1. Field of the Invention
The invention relates to a projection system, a touch module, and a touch method of the touch module. More particularly, the invention relates to a projection system, a touch module, and a touch method of the touch module using a laser beam.
2. Description of Related Art
In recent years, as information technology, wireless mobile communication, and information appliances have been rapidly developed and applied, various information products have utilized touch modules as input devices in replacement of conventional input devices, such as keyboards or mice, so as to ensure the convenience, the compactness, and the user-friendly design of the information products. The touch module can be generally categorized into a resistive touch module, a capacitive touch module, an optical touch module, a sound wave touch module, an electromagnetic touch module, etc, and the touch mechanism of the optical touch module is adapted to a large-sized display panel. The increasing size of the existing display panel contributes to the popularity of the optical touch module.
In general, the optical touch module senses the location of a touch point by two image sensors at different corners of the touch region, and thus one single touch point is detected in a normal manner. However, if there are multiple (i.e., two or more) touch points in the touch region, a ghost point issue arises, which leads to inoperability of or erroneous detection by the optical touch module. If it is intended to resolve the ghost point issue or achieve the multi-touch function, the quantity of the image sensors is increased. The increase in the quantity of the image sensors, however, often increases the hardware costs and raises the operation complexity of touch points. Besides, the maximum number of image sensors is subject to the volume and the structure of the touch module. Hence, how to achieve the multi-touch function under the conventional limitations of the volume and the structure of the touch module has to be taken into consideration in process of designing the optical touch module.
U.S. Pat. No. 5,525,764 discloses an image processing system with a handwriting input function and a method of manufacturing the image processing system. In the system, handwritten data are transmitted to a microprocessor which marks the handwriting locations on an image by certain colors according to the coordinates of the handwriting locations and the width of the handwriting locations, so as to create a new image combining the handwritten data and the original image.
U.S. Patent Application Publication no. 20100207876 discloses a laser scanner input device that includes a horizontal laser scanner device, an image capturing device, and a microprocessor. In the laser scanner input device, a laser beam is applied to horizontally scan an object, and the image capturing device is applied to capture an image reflected by the object. The laser scanner input device further calculates and obtains the coordinate of the object by the microprocessor, and the calculated coordinate serves as the corresponding input data.
China Patent Publication no. 102184060 discloses an optical touch device in which retro-reflectors are configured at three edges of a baseplate of a touch member, and an infrared laser head and a brightness sensor are located at two top corners on the other edge. A reflection mirror that scans the entire display region is configured on a rotatable mechanical device. A laser beam is blocked and reflected to the brightness sensor if a touch object is in the display region. According to the brightness information received by the brightness sensor and the brightness information fed back by the rotatable mechanical device, it can be determined whether there exists an object on the display region.